Robotic electrostatic painting systems for conductive paints fall into two broad categories: “direct charge” systems which apply an electrostatic charge directly to an amount of paint that is electrostatically isolated from ground; and “indirect charge or corona charging” systems which use electrodes to apply or induce a charge on a paint spray cloud in such a way that the paint can be continuously supplied from a grounded paint supply.
This invention relates to a specific problem that exists for “direct charge” systems that employ two or more reservoirs for holding the conductive paint, wherein the two or more reservoirs are mounted in close proximity to each other on a robot arm of the robotic electrostatic painting system. In this configuration, it is desirable to enable a state in which one reservoir is isolated from ground potential and electrostatically charged to perform a painting operation while another reservoir is grounded while being filled with conductive paint from a grounded paint supply. The most advantageous location for these two (or more reservoirs) is near each other, usually mounted on the same link of the robot arm used for applying the paint to an object such as a vehicle body.
Two (or more) such reservoirs, mounted, by necessity, so close together produce a very strong electric field when one reservoir is charged and the other(s) are grounded. Over time this electric field can cause deterioration of painting components thereby compromising the system. This deterioration is sometimes called “electrostatic etching” or “pinholing,” and ultimately results in a ground path or short circuit between the reservoirs, preventing the effective charging of the dispensing reservoir.
Electrostatic etching of seals or enclosures can occur in a matter of several minutes or can develop over many months of service, depending on the design and circumstances of use. To be included in a reliable system for industrial use, the components of the robotic electrostatic painting system in close proximity to the reservoirs must resist such deterioration for a minimum of several months of use.
Accordingly, it would be desirable to produce a barrier system for electrostatically insulating adjacent conductive paint reservoirs from one another to prevent the formation of a ground path or short circuit between the adjacent conductive paint reservoirs.